1. Field of the Invention
The invention is concerned with local bone regeneration for long bones. More specifically, the invention relates to the use of locally-applied vacuum to stimulate osteoblastic activity in long bones with discontinuity defects.
2. Description of Related Art
Osteogenesis, the growth of new bone, is a part of the normal healing process, and involves recruiting and activating osteoblast cells in the bone. This can be a slow process, particularly in the elderly and after severe trauma to the bone and after disease. The ability to accelerate osteogenesis would speed the healing process after trauma and after orthopedic and dental procedures. Methods to accelerate the process, particularly in local areas of bone, have been a holy grail for scientists for many years.
Current techniques of bone regeneration include: traditional methods such as distraction osteogenesis in which bone is pulled in an appropriate direction to stimulate growth, and bone grafting; and, experimental techniques that include use of drugs such as OP-1 that stimulate osteoblasts, implanting biomaterials laced with molecular signals designed to trigger the body's own repair mechanism, injecting bone marrow stem cells into the affected areas, and, transfusing cells that carry genes that code for bone-repair proteins. None of these methods are totally satisfactory, for a host of reasons. For a review of this subject see: Service, Science, 289:1498 (2000).
Distraction osteogenesis requires a bulky device and requires a very long period before positive results are seen. Bone grafting is limited by the quantity and quality of the patient's bone available for grafting. Biocompatible polymeric matrices without or with natural or recombinant bone morphogenic proteins suffer from a need for a very large and very expensive quantities of these signal proteins. The gene therapy procedure suffers from the general problems of gene therapy in general. The use of the stem cell approach is greatly limited by the scarcity and expense of such cells; for example, in 50-year olds, there is only one stem cell in 400,000 bone marrow cells. (see Service, 2000, above.)
Applicant has previously described a device that applies subatmospheric pressures to a fractured or lesioned area of a flat bone (e.g., scapula), and thereby promotes osteogenesis and consequent bone healing in such areas (Lytinas, U.S. Pat. No. 6,491,693, which is incorporated herein by reference). However, for anatomical reasons such a device is not suitable for non-flat long bones of the upper and lower extremities, particularly where blunt trauma from accidents and/or projectiles produces in the long bone discontinuous defects leaving gaps of 2.5 cm and more. In the past such discontinuous defects have been treated orthopedically by grafting into the discontinuity pieces of the bone taken from elsewhere in the body. More often than not, such grafting does not completely fill the discontinuity, thereby leading to poor healing (fibrous displacement) and shortened extremities.
Clearly, there is an acute need for a safe, simple, rapid, inexpensive and efficient device and method for producing osteogenesis in discontinuous regions of long bones. Such a device and method, based in principal on the vacuum technique discovered by the applicant (U.S. Pat. No. 6,491,693) has now been discovered, and is described below.